Evolution and the Origin of the 1 Ch 18 Species Nothing in Biology Makes Sense Except in the Light of Evolution Theodosius Dobzhansky 1900 1975 Be able to Summarize the observations reasoning and historical context that led to Darwin s theory of evolution by natural selection List and explain the main points of Darwin s Describe what is not in Darwin s Theory Describe and explain the scientific evidence that support the theory of evolution by natural selection Explain why Darwin s Theory is a scientific Theory theory Theory of Evolution A scientific theory is a broad well supported explanation with rich predictive value it leads to many accurate predictions E g Theory of Gravity is based on natural phenomena and causes stands up to experimental tests Misconception Species are always evolving into higher or better beings i e evolution is goal oriented Misconception Evolution creates new forms of life by dramatic mutations Misconception An organism can evolve during its lifetime Misconception An organism can influence the evolution of its own structures in response to its environment Misconception Evolution is a completely random process What is Evolution Evolution the change in organisms throughout earth s history Today s life is different from descended from earlier life descent with modification Views of Life Before Darwin Antiquity thru 1600 s Aristotle 384 322 B C fixed ideal species scala naturae ladder of nature Age of Reason 1700 s 1800 s Linnaeus Botanist 1707 1778 Orderly nested classification system Binomial naming Hutton and Lyell the earth is very old James Hutton Gradualism Charles Lyell Uniformitarianism James Hutton Geologist 1726 1797 slow continuous processes geological features gradualism CBJ Ch 22 14 Charles Lyell 1797 1875 Father of Geology uniformitarianism expanded Hutton s ideas today same geologic processes in past as Rate of change today rate of change in the past Thus earth is extremely old Lyell s popular Principles of Geology 1830 was read by Darwin Erasmus Darwin late 1700 s wrote ideas that forms minute slowly acquired complexity over time Charles Grandfather Organic life beneath the shoreless waves Was born and nurs d in ocean s pearly caves First forms minute unseen by spheric glass Move on the mud or pierce the watery mass These as successive generations bloom New powers acquire and larger limbs assume Whence countless groups of vegetation spring And breathing realms of fin and feet and wing The Temple of Nature 1802 Erasmus Darwin CBJ Ch 22 16 Lamarck Naturalist 1744 1829 Linked evolution to adaptation extinct species have been replaced by descendants w new features these adaptations helped them survive in environment Darwin agreed with these ideas Theory of inheritance of acquired characteristics through Use and Disuse If an organism changes during life in order to adapt to its environment those changes are passed on to its offspring Darwin rejected these ideas a giraffe s daddy stretched its neck longer to eat then passed it on Lamarckism Charles Darwin Naturalist on HMS Beagle 1831 1836 Travelled mostly to S America including Galapagos Islands Collected plants wildlife fossils Observed species geographic locales and adaptations Studied local geology Collection of different barnacles Extinct South American Mammal rhea in S Amer ostrich in Africa Evolution theory developed essay written in 1844 but not published in 1858 Alfred Wallace 1823 1913 letter to Darwin w same ideas from his work in Malay archipelago both presented scientific papers on natural selection together before the Linnean Society in 1858 Wallace Darwin Darwin s book Origin of Species 1859 Contains two main ideas 1 Descent with modification 2 Natural Selection Darwin s Theory Part 1 All present life is related through descent with modification from a common ancestor in past evolution not a totally new idea Charles Darwin Darwin s Theory Hyracoidea Hyraxes Sirenia Manatees and relatives Moeritherium Barytherium Deinotherium Mammut Platybelodon Stegodon Mammuthus Elephas maximus Asia Loxodonta africana Africa Loxodonta cyclotis Africa common ancestor of living elephants 60 34 24 5 5 2 104 0 Millions of years ago Years ago Extinction is common Part 2 Natural selection is the mechanism for evolution species Obs 1 Heritable variation exists in most Obs 2 All species produce more offspring than the environment can support based on Malthus s work Many offspring die before maturity Spore cloud variation easy to see here overproduction of offspring Inference 1 unequal reproductive success among individuals those w best traits help them survive reproduce in their environment leave more offspring than others Inference 2 Those heritable favorable traits adaptations accumulate over vast time matching the species to its environment adaptations Darwin s Natural Selection in one slide Observations Individuals in a population Organisms produce more vary in their heritable characteristics offspring than the environment can support Inferences Individuals that are well suited to their environment tend to leave more offspring than other individuals and Over time favorable traits accumulate in the population Theory of Evolution by Natural Selection explains both diversity and unity of life accounts for much of form and function can predict outcome of environmental change genetic variation is essential for evolution by Natural Selection Natural Selection In Action Antibiotic resistance in bacteria surviving S aureus gave rise to MRSA methicillin resistant Staphylococcus aureus NOT explained in Darwin s Theory 1 Origin of life 2 How variation arises 3 How inheritance works 4 Why variation still exists 5 Sudden changes in fossil record 6 Source of totally new characters Most of these are now explained Evidence of evolution Fossil record Homology Convergence Biogeography Molecular Biology The Fossil Record Many extinct spp no trilobites exist today species plural no dinosaurs exist today Fossil Intermediates Archaeopteryx 150 mya Avian and reptilian features Homology forms related by common ancestry Homologous structures structures derived from a common ancestor but may be modified for different functions These mammal forelimbs are homologous CBJ Ch 22 34 Vestigial structures remnants of ancestral homologous structures with no present adaptive function Ex blind cave salamanders have eyes Why infer descended from a species that could see Convergence unrelated spp have similar adaptations analogous